Coal tar soft pitch product



only of minor industrial importance.

United States Patent C "ice 2,851,894 COAL TAR SOFT PITCH PRODUCT No Drawing. Application July s, 1955 Serial No. 520,110

Claims priority, application Germany July 5, 1954 8 Claims. Cl. 106-279) The invention relates to a coal tar soft pitch product and to a process for the manufacture thereof, and also to mixtures of this coal tar soft pitch with distilled bitu- 2361304 Patented Nov. 25, 1958 components takes place differ slightly; for instance, separation into the components tar and bitumen usually takes place at a bitumen content of about Therefore, to exclude as far as possible separation into the components,Ya bitumen content of 15% of a bitumen of the type B45 is prescribed for road tars with a bitumen additive by the German Industrial Standards regarding bituminous binders for road construction (DIN 1995).

However, it is of considerable practical interest to provide compositions of bitumen and. tar of unlimited miscibility, when using types of bitumen such as they are'mentioned in DIN 1995, namely bitumen of the types B15, B45, B65, B80, B200 and E300, because a bitumen content of 15%, as set forth in DIN 1995, is too low to appreciably affect the properties of the soft pitch contained in the bitumen tars. Such different types of bitumen possess thefollowing properties:

Type of bitumen B300 B200 B80 B65 B45 B B15 1. Depltlh of penetration (100 g., 5 seconds, 25 C.) in one tenth of a 250-320 160-210 70-100 50-70 35-50 20-30 10-20 mi imeter 2. Softening point (ring and ball method) in 27-37 37-44 44-49 49-54 54-59 59-67 67-72 211. Softening point (Kraemer-Sarnow) in C 16-24 24-30 -35 -40 -45 -53 53-58 3. Breaking point (Fraass), at most, 0 20 15 10 8 6 2 +3 4. Ash content, at most, percent by weight 0.5 O. 5 0.5 0 5 0. 5 0. 5 0 5 5. Insoluble minus ash content, at most, percent by weight 0. 5 0.5 0. 5 0. 5 0. 5 0. 5 0. 5 6. Ductility:

at 15 0., at least, cm... 100

, at 25 0., at least, em 100 100 100 40 15 5 7. Paraffin content, at most, percent 1) w ht 2.0 2 0 2 0 2 0 2 0 2.0 2 0 8. Specific gravity at 25 0., at least 0.99 1.0 1.0 1.0 1.0 1.0 1.0 9. Loss in weight on heating at 165 C. for 5 hours, at most, perc t- 2. 5 2.0 1.5 1.0 1.0 1.0 1.0 10. Increase of Softening point (ring and ball method) after heating,

at most, C 10 10 10 10 10 10 10 11. Breaking point after heating, at most, C -15 -10 8 6 5 10 +5 12. Decrease in depth of penetration after heating, at most, percent 60 60 60 60 60 40 13. Duetility after heating:

at 15 0. atleast, cm

at 25 C. at least, cm

men. The term distilled bitumen as used hereinafter in the specification and in the claims designates the bituminous residue of normal petroleum distillation.

It is one object of the present invention to provide a coal tar soft pitch product which is miscible homogeneously and in practically any proportion with distilled bitumen and even with relatively soft bitumen. 50

purposes, while bitumen with a high melting point which 60 has been oxidized or distilled under a high vacuum is On the other hand large amounts of tar can also homogeneously be mixed with small amounts of bitumen. Thus, homogeneous miscibility between tar and distilled bitumen in 65 those proportions which are of industrial interest does not exist. Depending on the type of bitumen and tar used, the bitumen contents at which separation into the However,

Heretofore, however, it was not possible to increase the bitumen content of such tar-bitumen compositions. Consequently, even recently it was necessary to issue warnings against road tar compositions containing blended bitumen or soft bitumen, since failures in road construction projects have occurred when such mixtures were used. Such failures were due to the separation of the tar-bitumen inixtures into their components which had taken place (see, for instance H. Mallison, V. f. T.-Mitteilun gen, Strassenbau und Bautenschutz mit Steinkohlenteer, 1953, Issue 1, page 8).

It has now been found that a tar product homogeneously miscible in any proportion with distilled bitumen and even with relatively soft bitumen, i. e. a soft pitch product, is produced by mixing a coal tar pitch with a softening point (according to Kraimer-Sarnow) of -80" C. with a tar oil fraction which consists essentially of a mixture of quadrinuclear aromatic coal tar components. Such quadrinuclear aromatic substances are, for instance, chrysene, pyrene, fluoranthene, naphthacene, and others. Such tar oil fractions are, for instance, disclosed in -Brennstolfchemie, vol. 1953, page 38, and vol. 1955,

may I be used as '2 a tar oil fraction consisting essentially of quadrinuclear aromatic coal tar components in an amount sufficient to reduce the softening point of the soft pitch product to below about 40 C., which mixture represents an important object of the present invention, is homogeneous- 1y miscible with any type of distilled bitumen.

If a coal tar pitch is mixed according to the present invention with such an amount of a tar oil fraction consisting essentially of quadrinuclear aromatic .coaltarscomponents :thatthe softening point OflthG resulting mixture is lowered to. below..40 C., asoft .pitch product is formed'. which is compatiblein anyproportion, i. e. which is homogeneously miscible, with .the .bituminous residue of a.standard. petroleum :distillation. process known. to

;the-art.as.distilled bitumcn,-such as medium-hard-bitumen, foriinstance, of the typeB45, and .even softer types. It is another object of the present invention .to provide such a compositiontof a mixtureofqthemew soft pitch product. and .a distilled .bitumen.which;.composition is useful in road construction;

.The tar oil fraction used for preparingthe. soft pitch product according to the present invention ispreferably free ofsubstances .which precipitate in crystallineform 'on mixing .withthe coal ;tar pitch. A. tar.. oil-.fraction is therefore usedv in which its constituents arepin. eutectic equilibrium. The eutectic equilibrium may, if necessary, be produced by thoroughly cooling the oil and removing by centrifuging the crystallized solid substance.

The coal tar pitch to be employed according to the invention is preferably a pitch which has been obtained by continuous distillation under 'gentle thermal conditions (see, for instance, H. J.' Winkler Der steinkohlenteer und seine Aufarbeitung, Essen, 1951, pages 21- 24). It is also possible to use a pitch obtained by intermittent distillation. However, coal tar pitch obtained by distillation-under cracking conditions should not'be used, since the compatibility of such a coal tar. lpitch with distilled bitumen is the more diminished, the higher its content of cracking residues (soot-like compounds. of. high molecular weight).

The soft pitch product according to the invention can be mixed with the distilled bitumen without any special precaution and in any desired proportion.

. According to a further preferred. form of the present sisting essentially of a mixture 5 A softening point between about 60 the mixture to a softening point below 30" the softening point (according to Kraemer-Sarnow) of C. is used for the production of a tar-bitumen binder of low viscosity, and if a fluxing oil is added thereto, there is obtained a binding agent which combines the advantages of road tar and blended bitumen. In addition, such a composition is homogeneously miscible in any proportion with road tar as well as with blended bitumen.

What I claim is:

1. Soft pitch product homogeneously miscible in all proportions with distilled bitumen, said pitch product consisting essentially of a mixture of coal tar pitch with a softening point of about 70 C.,and a coal tar oil fraction consisting essentially of quadrinuclear aromatic coal tar components,- said soft pitch product having a softening point lower than about 40 C. i

2. The mixture. of distilled bitumen and a. soft pitch product in all proportions,said soft pitch product consisting essentially ofa mixture ofcoaltar pitch with a softening point between about 60 C. and about 80 C., and a coal tar oil fraction consisting essentially of quadrinuclear aromatic coal tar components, said soft pit h pr d t having. a. sof n n oi to e than a o 40 C.

1 3. I'he,;.mi xture of .,distilled bitumen and a soft .pitch product in all proportions, said soft pitch product consisting essentially of a mixture of coal tar pitch with a softening point of about 70 C., and a coal tar oil fraction consisting essentially of quadrinuclear aromatic coal tar components, said soft pitch product having a softening point lower than about 40 C.

4. The mixture of distilled bitumen and a soft pitch product in all proportions, said soft pitch product conof coal tar pitch with a CL and about 80 C.,

r and a coal tar oil fract on consisting essentially of quadrinuclear aromatic product. in all. proportions,

coal tar components, said soft pitch product having a softening point lower than about .40 C., said bitumen-pitch mixture containing between about 1% and about 6% .Of' an oil'rich in high boiling and high molecularuphenols.

5. ,The mixture of distilled bitumen ,and a soft pitch said soft pitch product con- .;sisting essentially of a mixture of coal'tar pitch with a invention a small amount of an oil with a high phenol V and a coal tar oil fraction consisting essentially of content is added tow-the mixture of soft pitch product .and bitumen. It, has .beenfoundthat the properties of the mixture of soft pitch product and bitumen are favorably atfected if 1% to 6% and preferably about 2% of an oil rich in phenols, cording to the 1 process disclosed in German. Patent No. 807,689, is added thereto; Such a preferred tar oil rich in phenol is produced, for instance, by distillation of equal parts of phenol pitch, i. e. the residueremaining on working upcrude phenol by distillation, and anthracene oil until the residue has the softening point of a normal pitch. i

As stated hereinabove any desired type of bitumen may be used for' the purpose of the present invention. Advantageously abitumen with a penetration value of 35-50 (100 g., 5 seconds, 25 C.) and preferably with a density higher than *1.03 at '20 C. is used. However, types of bitumen with a lower density are also suitable. The pitch-bitumen mixture according to the present invention, preparedby using a soft pitch product according to thisinventiomis suitable for, all the purposes for which pitch or bitumen or mixtures thereof are used. The composition according to the present invention such or in -mixture with light coal tar oils and may thus be adjusted to the viscosity of road tar or of blended bitumen.

If amixture ofequal amounts of coal tar-pitch (softening point 60-80 C.), bitumen (B45),.and atar oil fraction consisting-essentially :of quadrinuclear aromatic quadrinuclear aromatic coal t ar co for instance, an oil prepared acpitch product consisting essentially of am softening point between about 60 C. and about C.,

rnponents, said soft pitch product having a softening point lower than about 40 C., said bitumen-pitch mixture containing about 2% of an oil rich in high boiling and high molecular phenols.

6. In a process of producing a soft pitch product homogeneously miscible with bituminous distillation residues of thepetroleum distillation in all proportions the .step comprising; intimately mix'ng coal tar pitch with asofteri pointibetweenfiabout.60?C. and about 80 C. with a coal tar oil fraction consisting essentially ofquadrinuclear aromatic ooal targcomponentsg said coalltar oil frzictionbeing. added in an amount sufficient. to decrease the softening point ofthe resulting soft pitch; product below about, 40 C.

'7. ,Bituminoushroad surfacing material comprising a mixture of about equal parts of the bituminous distillation residue,;of the petroleum distillation and the, soft ixture of "coal tar pitch witha softening point of 'about; 70: C., and a coal tar;oil fraction consisting essentially .of quadri- .nuclear aromatic coalfl tar components, s aid soft, pitch product having a softening point lowerthan about 40 C., and a dilutingtar 'oil added to said mixture of; biturninous,distillationiresidue and softpitchproduct 1n an amount, sufiiclent to impart to said mixture the viscosity of road .tar.

. 8. .Soft..pitch product having .asoftening point Pf er than about; 40 C. and being homogeneously misc ble .withedistilled bitumenin all proportions, said soft p tch 6 product consisting essentially of a mixture of coal tar 924,086 Meadows et a1. June 8, 1909 pitch with a softening point of 60-80 C., and a coal tar 1,970,164 Breuer Aug. 14, 1934 oil fraction consisting essentially of quadrinuclear aro- 2,l23,560 Bennett July 12, 1938 matic coal tar components, said coal tar oil fraction be- 2,131,085 Anderton Sept. 27, 1938 ing admixed to said coal tar pitch in an amount sutficient 5 2,395,853 Fair Mar. 5, 1946 to decrease the softening point of said coal tar pitch to a softening point lower than about 40 C. FOREIQItI PATENTS 216,245 Great Britain May 29, 1924 References Cited in the file of this patent 358,974 Great Britain Oct. 12, 193} 10 363,698 Great Britain Dec. 21, 93 UNITED STATES PATENTS 538,308 Great Britain July 29, 1941 701,743 Lee June 3, 1902 601,784 Great Britain May 12, 1948 

1. SOFT PITCH PRODUCT HOMOGENEOUSLY MISCIBLE IN ALL PROPORTIONS WITH DISTILLED BITUMEN, SAID PITCH PRODUCT CONSISTING ESSENTIALLY OF A MIXTURE OF COAL TAR PITCH WITH A SOFTENING POINT OF ABOUT 70*C., AND A COAL TAR OIL FRACTION CONSISTING ESSENTIALLY OF QUADRINUCLEAR AROMATIC COAL TAR COMPONENTS, SAID SOFT PITCH PRODUCT HAVING A SOFTENING POINT LOWER THAN ABOUT 40*C. 